Efficient cobalt-catalyzed C–N cross-coupling reaction between benzamide and aryl iodide in water

Abstract

A practical and efficient strategy for the N-arylation of benzamide catalysed by a Co(C2O4)·2H2O/dmeda system in water is reported. Under the optimized conditions, a wide variety of N-arylated products were obtained in good yields (up to 92%) using substituted aryl iodides.

Air stable pincer (CNC) N-heterocyclic carbene–cobalt complexes and their application as catalysts for C–N coupling reactions

“…In catalysing aryl C-N coupling, the desire for environmentally friendlier reagents and to alleviate some shortcomings of the coupling strategies mentioned above has prompted chemists to seek alternative catalysts that involve the use of NHC-based complexes of environmentally benign metals like iron [18] and nickel [19]. Despite the rapid progress made in the use of cobalt and its salts as catalysts for C-C coupling reactions [20], the application of catalyst systems containing Co in aryl amination are quite rare [21] and to the best of our knowledge those containing pincer NHCCo complexes have not been reported. Very recent work by Tan and Teo [21] has reported a M A N U S C R I P T…”

“…Despite the rapid progress made in the use of cobalt and its salts as catalysts for C-C coupling reactions [20], the application of catalyst systems containing Co in aryl amination are quite rare [21] and to the best of our knowledge those containing pincer NHCCo complexes have not been reported. Very recent work by Tan and Teo [21] has reported a M A N U S C R I P T…”

“…Most synthetic chemists around the world have employed their palladium catalyst systems and it was only in the early 2000's that the first nickel catalysed amination reaction was reported [19a,b]. Transition metal catalytic systems containing cobalt are even rarer [10] and except for a few systems involving cobalt salts [21,39]; their application for activating C-N coupling reactions is scarce and to the best of our knowledge this is the first application of pincer NHC-Co complexes for C-N coupling reactions.…”

“…C-N coupling reactions have been conducted at high temperatures using a variety of solvents that include THF, dioxane, DMSO, DMF, toluene, and acetonitrile [15a,16b,19a-c,21] most of which are high boiling solvents and a major shortcoming in their use for this process. Except in some rare cases [21]; little or no success was reported for aryl C-N coupling with water as the solvent [16c].…”

Mild and Efficient Cobalt-Catalyzed Cross-Coupling of Aliphatic Amides and Aryl Iodides in Water

“…Our initial study began with the application of the previously reported conditions for the cobalt-catalyzed N-arylation 15 towards the cross-coupling of iodobenzene and 2-pyrrolidinone. To our delight, a modest yield of 50% of Narylated product was obtained ( Table 1, entry 1).…”